<style>
  .node text {
    font-weight: bold;
    fill : #FFF;
  }
  .node circle {
    cursor: pointer;
    fill: #fff;
    stroke: #f6962e;
    stroke-width: 1.5px;
  }
  path.link {
    fill: none;
    stroke: #ccc;
    stroke-width: 1.5px;
  }
</style>
<div id="pg_tree"></div>
<script type="text/javascript">
  var pg_ = (function()
  {
    var m = [20, 120, 20, 120],
      w = 1280 - m[1] - m[3],
      h = 700 - m[0] - m[2],
      i = 0,
      root;

    var tree = d3.layout.tree()
      .size([h, w]);

    var diagonal = d3.svg.diagonal()
      .projection(function(d)
    {
      return [d.y, d.x];
    });

    var vis = d3.select("#pg_tree").append("svg:svg")
      .attr("width", w + m[1] + m[3])
      .attr("height", h + m[0] + m[2])
      .append("svg:g")
      .attr("transform", "translate(" + m[3] + "," + m[0] + ")");

    d3.json("json/programmer.json", function(json)
    {
      root = json;
      root.x0 = h / 2;
      root.y0 = 0;

      function toggleAll(d)
      {
        if (d.children)
        {
          d.children.forEach(toggleAll);
          toggle(d);
        }
      }

      // Initialize the display to show a few nodes.
      //  root.children.forEach(toggleAll);
      //  toggle(root.children[1]);
      //  toggle(root.children[1].children[2]);
      //  toggle(root.children[9]);
      //  toggle(root.children[9].children[0]);

      update(root);
    });

    function update(source)
    {
      var duration = d3.event && d3.event.altKey ? 5000 : 500;

      // Compute the new tree layout.
      var nodes = tree.nodes(root).reverse();

      // Normalize for fixed-depth.
      nodes.forEach(function(d)
      {
        d.y = d.depth * 180;
      });

      // Update the nodes…
      var node = vis.selectAll("g.node")
        .data(nodes, function(d)
      {
        return d.id || (d.id = ++i);
      });

      // Enter any new nodes at the parent's previous position.
      var nodeEnter = node.enter().append("svg:g")
        .attr("class", "node")
        .attr("transform", function(d)
      {
        return "translate(" + source.y0 + "," + source.x0 + ")";
      })
        .on("click", function(d)
      {
        toggle(d);
        update(d);
      });

      nodeEnter.append("svg:circle")
        .attr("r", 1e-6)
        .style("fill", function(d)
      {
        return d._children ? "lightsteelblue" : "#fff";
      });

      nodeEnter.append("svg:text")
        .attr("x", function(d)
      {
        return d.children || d._children ? -10 : 10;
      })
        .attr("dy", ".35em")
        .attr("text-anchor", function(d)
      {
        return d.children || d._children ? "end" : "start";
      })
        .text(function(d)
      {
        return d.name;
      })
        .style("fill-opacity", 1e-6);

      // Transition nodes to their new position.
      var nodeUpdate = node.transition()
        .duration(duration)
        .attr("transform", function(d)
      {
        return "translate(" + d.y + "," + d.x + ")";
      });

      nodeUpdate.select("circle")
        .attr("r", 4.5)
        .style("fill", function(d)
      {
        return d._children ? "lightsteelblue" : "#fff";
      });

      nodeUpdate.select("text")
        .style("fill-opacity", 1);

      // Transition exiting nodes to the parent's new position.
      var nodeExit = node.exit().transition()
        .duration(duration)
        .attr("transform", function(d)
      {
        return "translate(" + source.y + "," + source.x + ")";
      })
        .remove();

      nodeExit.select("circle")
        .attr("r", 1e-6);

      nodeExit.select("text")
        .style("fill-opacity", 1e-6);

      // Update the links…
      var link = vis.selectAll("path.link")
        .data(tree.links(nodes), function(d)
      {
        return d.target.id;
      });

      // Enter any new links at the parent's previous position.
      link.enter().insert("svg:path", "g")
        .attr("class", "link")
        .attr("d", function(d)
      {
        var o = {
          x: source.x0,
          y: source.y0
        };
        return diagonal(
        {
          source: o,
          target: o
        });
      })
        .transition()
        .duration(duration)
        .attr("d", diagonal);

      // Transition links to their new position.
      link.transition()
        .duration(duration)
        .attr("d", diagonal);

      // Transition exiting nodes to the parent's new position.
      link.exit().transition()
        .duration(duration)
        .attr("d", function(d)
      {
        var o = {
          x: source.x,
          y: source.y
        };
        return diagonal(
        {
          source: o,
          target: o
        });
      })
        .remove();

      // Stash the old positions for transition.
      nodes.forEach(function(d)
      {
        d.x0 = d.x;
        d.y0 = d.y;
      });
    }

    // Toggle children.

    function toggle(d)
    {
      if (d.children)
      {
        d._children = d.children;
        d.children = null;
      }
      else
      {
        d.children = d._children;
        d._children = null;
      }
    }
  })();
</script>
